Abstract: In order to develope an optimum combination of water and fertilizer for winter wheat and summer corn, a field experimental research was carried out at Yongledian Water-Saving Irrigation Station in Beijing from 1998 to 2000. The effect of irrigation regimes and N application on yield, dry matter production, water productivity and N uptake was tested and analized. Nitrogen production efficiency was greatly related to soil moisture condition. At low water supplying levels(irrigating only at stem clongation stage), the highest fertilizer contribution ratio was obtained. Nitrogen production efficiency is decreasing with more fertilizer applied in all treatments. The highest water productivity was obtained under N-2 treatments and N-1 treatments. N-1 nitrogen treatment(e.i., 200 kg/hm²) in production management was proposed considering both the cost of nitrogen fertilizer input and nitrogen production efficiency.